let async = require("async");
async.auto({
    numbers: function(cb) {
        setTimeout(()=>{
            console.log("do numbers")
            cb(null, [1,2,3]);
        }, 2000)
    },
    strings: (cb)=>{
        setTimeout(()=>{
            console.log("do string");
            cb(null, ['a', 'b'])
        },1500)
    },
    assemble: ['numbers', 'strings', function(thus_far, cb) {
        console.log(cb)
        console.log(thus_far)
        cb(null, {
            numbers: thus_far.numbers,
            strings: thus_far.strings
        })
    }]
}, function(err, results) {
    console.log(results)
})